Showing papers by "Monash University published in 1976"

Terminating and exhaustive search in lexical access.

Abstract: Two experiments which test predictions derived from the assumption that lexical access involves a search process are reported. In the first experiment, test items must be classified as ambiguous or unambiguous, and in the second experiment, they are classified according to their syntactic properties. In both experiments, it is shown that when the target of the search is a nonexistent entry, an exhaustive search is involved, even though the test items are words. Further, in these conditions, frequency of occurrence is no longer related to decision time, as it is in lexical decision experiments. It is concluded that the search model adequately explains the procedure whereby the most common meaning of a homograph is accessed, but that the less common meaning is accessed in some completely different manner.

A late pleistocene and holocene pollen diagram from lynch's crater, northeastern queensland, australia

Abstract: SUMMARY The pollen diagram from Lynch's Crater extends the climatic and vegetation record for the Atherton Tableland back to about 60,000 years B.P. Subtropical rain forest, with abundant Araucaria, was present around the site from before 60,000 B.P. to about 38,000 B.P. and existed under about half the present-day annual rainfall. This was replaced by sclerophyll vegetation between 38,000 and 27,000 B.P. as a result of a decrease in precipitation, a decrease in temperature or the activities of aboriginal man. In any case the agent of rain forest destruction was probably fire. The record for the last 10,000 years or so is probably incomplete and radiocarbon dates unreliable, but changes during this period are in broad agreement with those evidenced from previously described sites within the area. The sequence from Lynch's Crater provides a basis for the interpretation of many problematical features of present-day vegetation distributions.

The visual analogue scale for anxiety: a validation study.

Abstract: The quest for accurate measures of anxiety has produced many scales, though very few which are‘both brief and valid and can be used for frequent and repeated measurements. McReynolds (1 968) in an extensive review of 88 formal anxiety assessment procedures noted the less than satisfactory status of anxiety assessment technology, and also concluded that relatively simple and straightforward self-rating measures often represent the techniques of choice, particularly in the measurement of current anxiety. One self-rating scale ideally suited to frequent and repeated measurements is the visual analogue or graphic rating scale, described over 50 years ago (Freyd, 1923) but relatively little used in clinical contexts until recently. Six recent studies (Zealley and Aitken, 1969; Crawford Little and McPhail, 1973; Folstein and Luria, 1973; Byrne, 1975; Davies, Burrows, and Poynton, 1975; Luria, 1975) have shown the visual analogue scale to be a valid and reliable measure of depressive mood. In two of these studies (Folstein and Luria, 1973, Davies et al., 1975) the visual analogue scale was also used as a measure of anxiety, with unimpressive results. Both studies used as the criterion measure the Manifest Anxiety Scale (Taylor, 1953) which may be considered a measure of trait (characteristic) rather than state (current) anxiety.

Anti-actin stains synapses

Abstract: SMOOTH muscle antibody (SMA) found in the sera of some patients with active chronic hepatitis (ACH)1 has been shown to contain specific anti-actin antibody2,3. These SMA sera have been used to demonstrate the presence of the corresponding antigen in normal2 and neoplastic4–6 ‘non-muscle’ tissues. We have demonstrated that SMA serum reacts with normal, neoplastic and foetal astrocytes but not with neurone cell bodies5,7. The present report deals with the reaction of SMA with synaptic endings in the central nervous system (CNS).

Isolation of renin granules from rat kidney cortex and evidence for an inactive form of renin (prorenin) in granules and plasma.

Abstract: Renin was demonstrated in particles having a sedimentation velocity similar to that of mitochondria during differential centrifugation. Further purification by isopycnic gradient centrifugation separated renin granules from the bulk of mitochondria and lysosomes, as well as from microsomes and cytoplasm. The density of renin granules was 1.202, which differed from the mean equilibrium densities of mitochondria (1.175) and lysosomes (1.170 and 1.230) in the heavy granule fraction. In studies involving gel filtration and polyacrylamide gel electrophoresis, renin granules appeared to contain an inactive form of renin that could be activated by acid treatment, had a higher apparent molecular weight than renin, and may be a more basic molecule. Inactive renin was also studied in plasma by electrophoresis and may originate from renin granules after exocytosis by the juxtaglomerular cells. Inactive renin may be a biosynthetic precursor (prorenin) and may be activated within the cell by a specific protease conseq...

The components of the Poggendorff illusion.

Abstract: An explanation of the Poggendorff misalignment illusion in terms of three basic components, the horizontal-vertical, longitudinal-transverse and obtuse angle effects, is proposed. It is argued that these effects amy either singly or jointly give rise to an apparent elongation- contraction of the space between the aligned elements with consequent change in apparent oblique direction. Experimental evidence for the involvement of the three components in various combinations and for modification of perceived direction between the transversals is presented. It is shown that the illusion in various forms of the Poggendorff figure can be accounted for by the involvement of one or more of the three components, each of which can be demonstrated independently of the illusion. It is suggested that other classical illusions, including the Muller-Lyer, might also be analysed in terms of basic components.

Cytokinesis in the developing wheat grain; Division with and without a phragmoplast.

Abstract: Cell wall formation during the transition from free-nuclear to cellular endosperm of wheat (Triticum aestivum L. cv. Heron) was investigated using correlated light and electron microscopy. Partitioning of the multinucleate syncytium that lines the inner periphery of the embryo sac is initiated 1-2 days after anthesis. Wall ingrowths, at first recognizable in sections as minute wall pegs, furrow inward from the edge of the embryo sac through the vacuolate cytoplasm which, to the inside, is clearly delimited by the central vacuole. Growth of the walls at this stage is independent of a phragmoplast and in this respect is reminiscent of the cleavage processes of lower plant cells. Intense fluorescence of the walls after staining with aniline blue suggests that callose may be a principal component. The growing walls branch and eventually meet on the side nearest the central vacuole. Cellularization of the peripheral layer of endosperm cytoplasm is thus complete about 2 days after anthesis. Between 2 and 3 days after anthesis, the peripheral layer of cells commences to divide both radially and tangentially and by 4 days the entire embryo sac is cellular. Cytokinesis during this phase entails the formation of a cell plate between sister nuclei. At the periphery of a forming cell plate, "vesicles" appear scattered amongst an array of phragmoplast microtubules. This mechanism of wall growth differs markedly from the initial infurrowing of the first-formed walls. The overall timing and the manner of cell wall deposition vary in a number of important respects from the model recently proposed by Mares et al. whose work was based largely on light microscopy (D.J. Mares; K. Norstog; A.B. Stone: Aust. J. Bot. 23, 311-326, 1975).

The sleep habits, personality and academic performance of medical students

Abstract: The academic performance of 104 fourth-year medical students was assessed in relation to their sleep habits reported in a questionary and their scores on the Minnesota Multiphasic Personality Inventory. Poorer academic performance was related significantly to later times of waking up in the morning, particularly at weekends, and to subjectively poorer quality sleep, but not to the amount of sleep usually obtained. Poor academic performance was related also to scores on scales 3 (hysteria), 4 (psychopathic deviate) and 8 (schizophrenia) of the MMPI. Simple enquiries about sleep habits may make it easier for students who are at greatest risk of academic failure to be identified and helped.

Renin substrate in granules from rat kidney cortex.

Abstract: 1. Subcellular fractions of rat kidney cortex generated angiotensin I continuously over 2h when incubated at 37degreesC with rat renin, indicating the presence of renin substrate within cells in the renal cortex. 2. Renin substrate was located in highest specific concentration in particulate fractions. The particles containing renin substrate had a sedimentation velocity slightly lower than mitochondria and renin granules but greater than the microsomal fraction. 3. Isopycnic gradient centrifugation indicated a density of 1.190g/ml for the particles containing renin substrate, compared with 1.201 for renin granules, 1.177 for mitochondria, and 1.170 and 1.230 for lysosomes in the heavy-granule fraction. 4. In the liver, renin substrate was also found in particles, but these had a lower sedimentation rate than those from the kidney. 5. The molecular weights of renin substrate in kidney and liver granules and rat plasma were similar, namely 61000-62000. 6. On the basis of these biochemical findings, a mechanism for the intrarenal production of angiotensin, incorporating a subcellular reaction scheme, is proposed.

Leaf structure and translocation of dry matter in a C3 and a C4 grass

Abstract: Dry weight analyses and 14CO2 were used to study translocation in leaves of the C3 grass Lolium temulentum L. and the C4 grass Panicum maximum Jacq. and the results related to the distribution and amount of phloem in the lamina. The rate of specific mass transfer rose from the tips to the bases of leaf blades, in both species high rates were recorded. Major veins were responsible for the bulk of longitudinal translocation and minor veins were important in collecting and loading photosynthate. Transverse veins stored 14C-assimilate and may have coordinated the functioning of the longitudinal veins. The bearing of the results on the mechanism of translocation is discussed.

Apparent length of the arms of acute and obtuse angles, and the components of the muller-lyer illusion

Abstract: Muller-Lyer first drew attention to differences between the apparent length of lines bounding angles of different sizes. This simple form of his illusion was investigated in Experiments 1 and 2 in which the angle between a horizontal 50-mm test line and an attached inducing line was varied between 0 and 180 in 15 steps. With acute angles the test line was underestimated relative to a plain line and with obtuse angles overestimated. Maximum effects were found for angles of about 30 and 150 with the magnitude of overestimation exceeding that of underestimation. In Experiments 3 and 4 the contribution of the angle effect in more complex figures was investigated using figures consisting of one, two and four angles, the last being the conventional Muller-Lyer figures. In acute angle figures (Experiment 3) the illusion appeared to be due to two components, that due to angle and that due to the longitudinal space enclosed between the obliques but in obtuse angle figures it appeared to derive from the ad...

Renin-angiotensin and kallikrein-kinin systems in sodium homeostasis and hypertension in rats.

Abstract: 1. Urinary kallikrein excretion was measured in rats by an enzyme kinetic method employing radioimmunoassay of generated bradykinin. 2. Rats given a sodium load (NaCl solution, 20 g/l, to drink) for 28 days showed acute and prolonged significant falls in urinary kallikrein excretion associated with suppression of plasma renin and angiotensin. 3. Conversely sodium-depleted rats showed increases in urinary kallikrein excretion, associated with rises in plasma renin and angiotensin. 4. A close and significant direct relation between plasma renin activity and urinary kallikrein excretion was demonstrated. 5. The diuresis and natriuresis induced by frusemide in rats was associated with increased urinary kallikrein excretion and acute rises in plasma renin. 6. In chronic renal hypertensive rats urinary kallikrein excretion was increased only in the animals with two-kidney Goldblatt hypertension. This group was also the only group that demonstrated a significant rise in plasma renin activity.

Computer controlled muscle relaxation: a comparison of four muscle relaxants in the sheep.

Abstract: Computer control of anaesthesia has been extended to include muscle relaxant drugs. Injection of d-tubocurarine, gallamine, alcuronium or pancuronium was controlled by computer to reduce the integrated electromyogram to a preset level (40 per cent of control) for one hour. A programmed level of muscle paralysis is therefore possible for use in physiological and pharmacological experiments, and in clinical practice where precise control of the degree of paralysis together with minimal dosage is advantageous.

Gravity as the sole navigational aid to the newborn quokka.

Abstract: ALTHOUGH there is general agreement on the sequence of events at birth for several marsupial species1, it is still not known how the newborn joey navigates on its journey from the mother's cloaca to her pouch. Frith and Calaby2 have postulated that, at birth, the red kangaroo (Megaleia rufa) “… has large nostrils and presumably a well developed sense of smell which probably plays a major part in its location of the pouch”. On the other hand, Hartman3 has suggested that the newborn opossum (Didelphis virginiand) was “negatively geotropic” though he has now modified this view considerably4, as histological studies have revealed that the vestibular apparatus of the newborn animal is undirTerentiated and therefore nonfunctional5,6. To investigate whether one of these mechanisms2,4 could account for the behaviour of the newborn quokka (Setonix brachyurus) we have observed parturition in this macropodid marsupial.

Stimulation of sodium and water secretion without inhibition of glucose absorption in the rat jejunum by vasoactive intestinal peptide (VIP).

Abstract: 1. Infusion of vasoactive intestinal peptide (VIP) into the arterial blood supply of the small intestine in anesthetized rats did not alter either the perfusion pressure in the superior mesenteric artery or the active absorption of glucose from the jejunum, but did produce a large net secretion of Na+ and water into the lumen of the jejunum. 2. The results are compared to the effects of prostaglandin E1 which stimulates Na+ and water secretion and inhibits glucose active absorption in the rat jejunum.

Balance studies of nine elements during complete intravenous feeding of small premature infants.

Abstract: James, B. E. and MacMahon, R. A. (1976).Aust. paediat. J., 12, 154–162. Balance studies of 9 elements during complete intravenous feeding of small premature infants. During the course of a study of complete intravenous feeding of premature infants weighing less than 1,050 g, metabolic balance studies were performed on 4 surviving infants for 5 major nutrient elements: sodium, potassium, calcium, magnesium and phosphorus; and 4 trace elements: iron, zinc, copper and manganese. These studies determined the amounts retained when these elements were given intravenously. There was a significant correlation between the input and retention of each of these elements except zinc, and the data obtained have been used to derive tentative recommendations for the rate of infusion of these elements into the small premature infant.

Synthesis and bromodemercuration of some permercurated arenes

Abstract: Pentabromonitrobenzene, pentabromobenzoic acid, pentabromobenzamide, pentabromoacetanilide, barium pentabromobenzenesulphonate, 1,2,4,5 - tetrabromo -3-chloro-6-(trifluoromethyl)benzene, 2,3,5,6-tetrabromo-4-methoxytoluene 2,3,5,6-tetrabromo-4-methoxybenzamide, methyl 2,3,5,6-tetra- bromo-4-methoxybenzoate, and 1,2,5-tribromo-3,4-dichloro-6-fluorobenzene have been synthesized in good yield by bromodemercuration of the corresponding fully mercurated (permercurated) arenes, e.g. C6(HgO2CCF3)5NO2, which were prepared by reaction of an excess of molten mercuric tri- fluoroacetate with suitable arenes at c. 180-245o. Permercuration of p-methoxybenzoic acid was accompanied by complete decarboxylation giving, after bromodemercuration, pentabromo(methoxy)- benzene, which was also obtained in low yield from preparations of methyl 2,3,5,6-tetrabromo-4- methoxybenzoate and 2,3,5,6-tetrabromo-4-methoxybenzamide. Conditions have been devised for conversion of phenylmercuric chloride into either a pentamercurated or a hexamercurated benzene derivative, and hence into pentabromo-or hexabromobenzene. The results establish permercuration/bromodemercuration as a simple and versatile route to polybromobenzene.

The effect of age on the reversibility of cellular atrophy in the LGN of the cat following monocular deprivation: A test of two hypotheses about cell growth

Abstract: Monocular closure soon after birth is known to reduce the growth of the deprived cells in the LGN provided that there are competing cells with normal input. When the closed eye was opened and the open eye closed after three of six weeks of monocular closure, the originally deprived cells in the LGN were able to recover their normal size. However, it was found that after 14 weeks of monocular closure there was no recovery. The ability of the initially closed eye to excite cells in the visual cortex is known to depend on the age when eye closure is reversed in a similar manner. Thus the growth of cells in the LGN is correlated with the possession of effective synapses upon cortical cells. This result is compatible with the possession of effective synapses upon cortical cells. This result is compatible with the hypothesis that competition occurs at the cortical level. It is argued that the alternative hypothesis of competition within the LGN predicts reversibility at any age. In some kittens, the closed eye was opened and the opposite optic nerve crushed. Some evidence was then found of structural recovery even after 14 weeks of deprivation. The hypothesis of cortical competition predicts functional recovery in such kittens, but this remains to be tested.

Release of renin from glomeruli isolated from rat kidney

Abstract: 1. Glomeruli free from renal tubules and cell debris were isolated in large numbers from rat kidney cortex by a rapid, simple process of graded sieving on stainless steel meshes. 2. Glomeruli were viable, had fragments of the arterioles attached and contained renin. 3. Glomeruli, when incubated, released renin into the medium. Using a super-fusion technique this was shown to be time dependent until a basal secretion level was achieved. 4. Release of renin was directly proportional to the number of glomeruli and could be stimulated by isoprenaline, adrenaline and noradrenaline in order of the potency of their action on beta-adrenoreceptors. 5. Isolated glomeruli were therefore established as a useful model system for studying the release of renin by direct influences on the juxtaglomerular cells where haemodynamic, tubular and extrarenal influences are removed.

An exact and a new first-order solution for the relative trajectories of a probe ejected from a space station

Abstract: The motion of an unpowered probe, ejected into an elliptic orbit in the orbital plane of a space station in circular orbit, is investigated from a reference system attached to the space station. Existing approximate solutions to this relative trajectory problem, of two bodies in Keplerian orbits about the same primary, are restricted to small relative displacements. A new first-order solution is derived from an exact solution: no restriction is placed on the relative displacement and the solution osculates with the exact solution at points corresponding to perigee and apogee of the probe's orbit. A geometrical description of the trajectories is given in terms of prolate cycloids plotted in a curvilinear coordinate system.